Screen doors are available in a variety of materials, including metal, typically aluminum, and which tends to corrode, and wood, often from rain forest trees and which requires painting from time to time. Newer screen doors are made of foamed polymer and do not need to be painted but have their own drawbacks.
Screen doors made of foamed polymer are otherwise similar in appearance to conventional screen doors. They have two stiles (vertical members) and at least two and often three rails (horizontal members) formed into a simple frame. To join the stiles and rails at corners, either wooden dowels or screws with wooden pegs, or a combination, are used to form the joint. Holes are drilled in the ends of the rails and in the sides of the stiles near their ends. Dowels are inserted in the holes. The ends of a stile and a rail are pushed together with the dowels running from one to the other to form a joint. Alternatively, they are fastened together using deep-set screws and then the holes above the screws are filled with plastic pegs to form the joint.
In time, the wood of the dowels can start to rot. Screen doors are invariably exposed to the elements so moisture will inevitably enter the joint. Eventually the joints will fail.
The screens of polymer screen doors are installed by forcing them into grooves routed into one side of the stiles and rails of the screen door frame. The screen is held in place in its groove by a rubber spline. The rubber spline, being resilient, is compressed when pressed into the groove and thus holds the screen in place by friction. However, the spline and the screen can be pulled out if sufficient force is applied in a direction normal to the screen. Typically, the repeated pressure of someone's hand on the screen to open the screen door will gradually cause the screen to deform, or bag, until eventually it loosens.
Thus, there is a need for a better foamed polymer screen door, one in which the door's joints and screen securement are as durable as the foamed polymer of the frame.